Contemporary labor patterns: the impact of maternal body mass index.

Department of Obstetrics and Gynecology, University of Illinois at Chicago, Chicago, IL, USA. Mkomin1@uic.edu

Abstract

OBJECTIVE:

We sought to compare labor patterns by body mass index (BMI).

STUDY DESIGN:

A total of 118,978 gravidas with a singleton term cephalic gestation were studied. Repeated-measures analysis constructed mean labor curves by parity and BMI categories for those who reached 10 cm. Interval-censored regression analysis determined median traverse times, adjusting for covariates in vaginal deliveries and intrapartum cesareans.

RESULTS:

In the labor curves, the time difference to reach 10 cm was 1.2 hours from the lowest to highest BMI category for nulliparas. Multiparas entered active phase by 6 cm, but reaching this point took longer for BMI ≥40.0 (3.4 hours) compared to BMI <25.0 (2.4 hours). Progression by centimeter (P < .001 for nulliparas) and from 4-10 cm (P < .001 for nulliparas and multiparas) increased as BMI increased. Second stage length, with and without an epidural, was similar among BMI categories for nulliparas (P > .05) but decreased as BMI increased for multiparas (P < .001).

CONCLUSION:

Labor proceeds more slowly as BMI increases, suggesting that labor management be altered to allow longer time for these differences.